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Absolute Black’s been teasing us with quite a few gorgeous CNC machined parts, from pedals to brake rotors (CenterLock and 6-bolt) to chainrings. Now, we’ve got hands (and chain) on the rings for some actual weights and first impressions.

The differentiating point for AB’s rings is the tooth profile. It’s taller than regular chainrings, and the actual shaping is unique. The idea is that it precisely fits between the chain’s pins and takes up any slack, reducing the likelihood the chain will fall off. Combined with a clutch-style rear derailleur, AB founder Marcin says they’ll keep the chain on just fine while saving a ton of weight compared to a standard spider-plus-chainring setup.

Do the claims hold up? So far, pretty well. They’re light and keep the chain on for aggressive XC riding. Read on for actual weights, comparisons and plenty more…

WEIGHTS & DETAILS

The tooth profile is designed to basically capture the chain and hold it securely as it moves around, then release freely upon exit. Marcin sent this image of just four links worth of contact holding onto the chain enough to carry the weight of a water bottle:

At first, we thought this might induce chainsuck or add “drag” to pedaling effort, but that doesn’t seem to be the case. It works as advertised.

Our 34t chainring came in at just 67g.

For comparison, if you were running a standard X0 2×10 setup and switched to this, the end result would be a GXP crank plus ring weight of about 350g, a savings of 123g…not to mention the loss of the front derailleur, shifter, cable and housing. It adds up quick.

The chainrings are CNC’d from 7075 TXXX alloy, then hard anodized to 30um. Marcin says this makes them extremely hard, and then they’re colored. They’re available in 28/30/32/34 tooth counts (36 coming), create a 49mm chainline and are offered in blue, red and black. Green and gold may come soon. US retail is $60 each. They do recommend a chainguide for more aggressive or gravity riding.

RIDE REVIEW

AB says they’ll work with any SRAM direct-mount crankset that’s GXP or the longer BB30 spindle. I’ve mounted them to both with no problems, but they warn that the shorter BB30 spindles (which use a 10mm spacer on the driveside rather than 16mm) can create a chainline that won’t work well with chain guides.

The machining is both extensive and exquisite.

Marcin’s working on a wide/narrow XX1 style chainring for 104BCD spiders, too, but his original design has worked pretty well for us so far and results in a lighter overall system weight than spider+chainring. This one’s mounted on an XX1 BB30 crankset using XX1 rear derailleur. Racing around our local trails, which are full of roots and small drops and jumps, I haven’t dropped the chain yet. Well, once during a wipeout, but that happened with the XX1 chainring also.

On the bike, you can see the tops of the teeth poking through the chain. They’re supposed to work with 9/10/11 speed chains, and we’ve tested with 10 and 11 so far.

At first, there’s a bit of noise from the ring/chain interaction. It’s like a muted version of the sound your chain makes when it’s so dry or crummed up that it’s about to suffer chainsuck. Except that it doesn’t chainsuck. That noise is dying down a bit as we put more miles on it, and Marcin says the latest production batch eliminates it altogether.

Stay tuned for the long term review later in the year.

PROTOTYPE VERSION

Just for fun, Marcin also sent along this custom one originally made for a pro racer. It’s 0.3mm thinner and comes in ridiculously light:

46g for a 32t, which is 5g lighter than standard.

We haven’t had as much success keeping the chain on with this one, and can see just a bit of flex when we’re hammering. Under hard efforts, it has sent the chain off the outside six or seven times over several rides. With a chainguide, it shouldn’t be an issue, but it’s a non-production part anyway…we just thought it’d be fun to share.

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Comments

Sweet progress! Geez the single ring setups have made a lot of progress in the past two or three years. I still have a mrp guide and an old style X0 rear der. on mine. I’d love to try this ring with no guide and one of these new tight sprung derailleurs. Rock on.

the orange one clearly shows a traditional tooth shape, unlike the blue one.
the hanging assembly looks to be a string tied to the middle link, with the links to each side gripping the chainring. neat, but i just wonder if a standard track or bmx chainring could be made to do the same thing.

wait wait wait. so theyve re-invented the re-invented wheel? they are making a single ring chainring thats supposed to hold onto the chain better…and they put it on xx1 cranks…and they didnt use the narrow/wide profile?

Felipe – SRAM’s new derailleurs have a clutch on them for X7 through X0 I believe. Shimano also has one on at least the top three groups, using an on/off switch to make wheel changes easier. The benefit is stronger chain tension with minimal increase in shift lever effort. The benefit is less chain slap and, with single ring drivetrains, less chance that the chain can fly off the chainring.

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